This invention is directed to keyboards employing snappable plastic domes such as shown in U.S. Pat. No. 3,860,771 and is more particularly directed to a modification of the dome structure in said patent to achieve effective snapping of the dome in cases in which the actuator or button configuration is such that a good clean snap cannot be consistently achieved.
It has been found in practice that in order for a plastic dome of the shape shown in U.S. Pat. No. 3,860,771 to provide consistently good snap when depressed by an actuator portion of a button, the actuator portion should be of a configuration such that a sufficient surface area of the dome is being engaged during depression to effect snap.
In addition, it is also important that the button does not include other surfaces which may engage the dome while it is being depressed because this too will frequently cause poor snapping of the dome.
The present invention provides a solution to the aforementioned difficulties by providing a snap initiator at the top of the dome which will compensate for variations in the shape of the actuator. The snap initiator will in effect act as a portion of the actuator so that the forces caused by button depression are applied across the dome in a manner in achieve consistently good snap.